Why are all of the popular songs from my MP3 albums being methodically deleted?

I have a Nokia Lumia phone with X-box live music on it. I copied my own MP3 files onto it--files I had made from CDs I owned. Recently I went through my music files and found that certain files were missing--oddly enough, always the files that I most wanted to listen to. Rather than random files, it seems like anything that ever made the top 100 or was recognized as a somewhat popular song is gone. Examples:

Vince Guaraldi--everything's there except ALL the songs from the Peanuts movies. No "Linus and Lucy." No "Christmas Time is Here." Just schlocky covers of old people's music.
Badfinger's greatest hits--no deletions except for "No Matter What" and "Come and Get It." I mean, what else did they do that was worth listening to? "Without You" is there, but who listens to that after Nilssen covered it?
Fanfare Ciocarlioa's "Iag Bari"--everything's there except the song "Iag Bari."
Ramones--"All the Stuff." All the stuff except "Blitzkreig Bop" and "Sheena Is a Punk Rocker." Also "Judy is a Punk" is gone for some reason, even though it wasn't popular. "Let's Dance" is still there, but I bet it's gone by next month.
"Animals" has been reduced to "Pigs on the Wing" 1 and 2, and "Sheep."

It goes on like that. Albums I haven't listened to in years, and have never accessed on this phone have been stripped of their most popular songs--down to obscure Balkan music that no one has ever heard of.

I have a Nokia Lumia phone with X-box live music on it. I copied my own MP3 files onto it--files I had made from CDs I owned. Recently I went through my music files and found that certain files were missing--oddly enough, always the files that I most wanted to listen to. Rather than random files, it seems like anything that ever made the top 100 or was recognized as a somewhat popular song is gone. Examples:

Vince Guaraldi--everything's there except ALL the songs from the Peanuts movies. No "Linus and Lucy." No "Christmas Time is Here." Just schlocky covers of old people's music.
Badfinger's greatest hits--no deletions except for "No Matter What" and "Come and Get It." I mean, what else did they do that was worth listening to? "Without You" is there, but who listens to that after Nilssen covered it?
Fanfare Ciocarlioa's "Iag Bari"--everything's there except the song "Iag Bari."
Ramones--"All the Stuff." All the stuff except "Blitzkreig Bop" and "Sheena Is a Punk Rocker." Also "Judy is a Punk" is gone for some reason, even though it wasn't popular. "Let's Dance" is still there, but I bet it's gone by next month.
"Animals" has been reduced to "Pigs on the Wing" 1 and 2, and "Sheep."

It goes on like that. Albums I haven't listened to in years, and have never accessed on this phone have been stripped of their most popular songs--down to obscure Balkan music that no one has ever heard of.

What the heck? Did I forget to wear my foil hat or something?

what happens if you copy one of those songs back to the phone in the same location? Can you try that?

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